Added changelog information
Added changelog information

lyrixx/recurly-client-php,developer-devPHP/recurly-client-php,JasonGhent/recurly-client-php,phpdave/recurly-client-php,developer-devPHP/recurly-client-php,cgerrior/recurly-client-php,overblog/recurly-client-php,jcoby/recurly-client-php